USH2A and retinitis pigmentosa 1: However, a study in the U.K. showed that the USH2A-associated USH II cases exhibited similar retinopathy to the USH2A-associated non-syndromic RP cases, although the audiological phenotype differed, and some USH2A mutations were predominantly associated with non-syndromic retinal degeneration (i.e. they were RD-specific) [25].